Bug FAQUltronia Underwing
Catocala ultronia · Order: Lepidoptera · Family: Erebidae
Also called: Ultronia Underwing Moth
Source: Wikipedia
The dark red underwing has a wingspan of about 46 to 60 mm. Adults are seen flying in August, producing one generation per year depending on location. It lives across most of eastern North America, extending south to Florida and Texas and west to southeastern British Columbia.
Source: Wikipedia
How to recognize it
Catocala ultronia, known as the dark red underwing, belongs to the moth family Erebidae.
Source: Wikipedia
Size
Its wingspan ranges from 46 mm to 60 mm.
Source: Wikipedia
Where it lives
It is found throughout most of eastern North America, reaching south to Florida and Texas.
Source: Wikipedia
What it eats
Caterpillars feed on ash, apple, poplar, several cherry species, and American basswood.
Source: Wikipedia
Life cycle
Adults appear in August and produce one generation per year, varying with location.
Source: Wikipedia
When you see it
Adults are on the wing in August.
Source: Wikipedia
Where it comes from
Its native range includes the eastern United States and southern Canada, extending to extreme southeast British Columbia.
Source: Wikipedia
Lookalikes
It is a moth of the family Erebidae, commonly called the dark red underwing.
Source: Wikipedia
Where it is found in the US
Recorded in 43 of 51 states and DC. Most records: Pennsylvania, Massachusetts, Michigan, Connecticut, Ohio, New York, Virginia, New Jersey.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in United States; native in Canada. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
When can I see adult dark red underwings?
Adults are active in August, producing a single generation each year.
Source: Wikipedia
What trees do the caterpillars eat?
The larvae feed on ash, apple, poplar, several cherry species, and American basswood.
Source: Wikipedia
Where is this moth found?
It occurs across most of eastern North America, from Florida and Texas up to southern Canada and into southeastern British Columbia.
Source: Wikipedia
Same family (Erebidae)
Spongy MothLymantria disparDamages trees, gardens or crops
Fall Webworm MothHyphantria cuneaDamages trees, gardens or crops
Brown-tail MothEuproctis chrysorrhoeaCan irritate skin
Isabella Tiger MothPyrrharctia isabella
Virginian Tiger MothSpilosoma virginicaCan irritate skin
Salt Marsh MothEstigmene acreaSources
- Wikipedia: https://en.wikipedia.org/wiki/Catocala_ultronia
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-23 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-23.